Genetic testing for Lynch syndrome in the first year of colorectal cancer: a review of the psychological impact

Landsbergen KM, Prins JB, Brunner HG, Kraaimaat FW, Hoogerbrugge N

CRD summary

This review concluded that there was limited available evidence on the psychological impact of genetic testing for Lynch syndrome on recently diagnosed patients with colorectal cancer. Given the lack of study quality assessment, the possibility of missed studies or biases affecting the review results, the reliability of the authors' conclusions is uncertain.

Authors' objectives

This abstract only addresses the research question relating to genetic testing that meets the DARE criteria: to assess the psychological impact of genetic testing for Lynch syndrome on patients diagnosed with colorectal cancer.

Searching

The following databases were searched from January 1997 to October 2007: PubMed, PsycINFO, EMBASE and the Cochrane Library. Search terms were reported. Only studies published in English, French or Dutch were considered for inclusion.

Study selection

Studies of genetic testing on patients diagnosed with colorectal cancer that evaluated psychological outcome measures were eligible for inclusion. Studies of pre-symptomatic/predictive testing and genetic testing for familial adenomatous polyposis were excluded, as were qualitative studies. Studies were also excluded if there were no relevant data. The outcomes reported in the review included attitude towards genetic testing, anxiety, distress and depression.

Included studies used various questionnaires to assess the psychological impact. Most of included studies only measured distress before disclosure of the genetic test result. Most of included patients were diagnosed with colorectal cancer several years prior to the study. Where reported, the mean age of included patients ranged from 42 to 64 years.

One reviewer assessed studies for inclusion.

Assessment of study quality

The quality of studies was assessed using the guidelines for levels of evidence by the Centre for Evidence-based Medicine (Oxford).

The authors did not state how many reviewers performed the validity assessment.

Data extraction

The authors did not state how the data were extracted, or how many reviewers performed the data extraction.

Methods of synthesis

The studies were combined in a narrative synthesis, grouped by different stages of genetic counselling.

Results of the review

Ten studies were included in the review (n=1,220 patients). The sample size ranged from 36 to 269 patients. The study quality was not reported.

Psychological reactions before genetic counselling: Three studies reported that patients with colorectal cancer tended to have positive attitude towards genetic testing. The concern about the risk of colorectal cancer in their close relatives was the most common motivation to take genetic testing; this motivation was strongly present in younger patients.

Psychological reactions before and after genetic counselling: Four studies showed that, although a small proportion of patients developed clinically relevant levels of anxiety and depression, most psychological distress scores remained within the normal range before the result of genetic testing was disclosed. The vulnerable patients were females and males diagnosed before the age of 50 years.

Psychological reactions after disclosure of the genetic test result: Two studies showed that disclosure of the genetic test result did not lead to any relevant psychological distress in most patients. The vulnerable patients were those with pre-test distress, a history of depression and high familial mortality from colorectal cancer.

Authors' conclusions

There was limited available evidence on the psychological impact of genetic testing for Lynch syndrome on recently diagnosed patients with colorectal cancer.

CRD commentary

The inclusion criteria for this review were not specified for study design, and the outcomes were broadly defined. Relevant sources were searched. Efforts were made to find published studies but not unpublished studies, introducing the potential for publication bias. The decision to only include studies in three languages meant that the risk of language bias could not be ruled out. No sufficient attempts were made to minimise the biases and errors in the review process, as only one reviewer performed the study selection.

The quality of included studies was not presented in the report; the authors reported using levels of evidence (on the basis of study designs), which did not assess the quality of individual studies. A narrative synthesis was appropriate given the diversity of included studies.

Given the lack of study quality assessment, the possibility of missed studies or biases affecting the review results, the reliability of the authors' conclusions is uncertain.

Implications of the review for practice and research

Practice: The authors stated that patients whose genetic tests disclose that they are Lynch syndrome mutation carriers may benefit from extra psychological counselling.

This is a critical abstract of a systematic review that meets the criteria for inclusion on DARE. Each critical abstract contains a brief summary of the review methods, results and conclusions followed by a detailed critical assessment on the reliability of the review and the conclusions drawn.